In the downhole drilling and completions industry, desired fluids, e.g., hydrocarbons, are often held in reservoirs or formations containing fluid stores composed also of undesirable fluids, e.g., water. In some cases the volume of water is several times that of the volume of hydrocarbons in a reservoir. Production of fluids from such reservoirs then roughly requires the transport and associated wear of several times the fluid that is actually desired, the fluids must be separated, and large quantities of the undesirable fluid dealt with. As a result, the industry well receives advances in fluid separation, particularly downhole fluid separation.